Diffusion Blocking Layer Research Articles

Polymorphic Engineering of MnO2 Structure as a Diffusion Blocking Layer for Selective Seawater Electrolysis

The water splitting via renewable energy is one of the sustainable process to generate the future clean energy in form of hydrogen. One of the key challenge for the large-scale water electrolysis is the availability of pure water. The sweater can be consider as an alternate feedstock for the large-scale water electrolysis. However, the presence of undesirable components like chlorides, bromides etc. are the potential challenge to make the use of seawater as a facile feedstock. As per the electrochemical potentials, chlorine evolution reaction (CER) along with the oxygen evolution reaction (OER) at the anode is one of the primary existing challenge in seawater electrolysis. Where thermodynamics favour OER and kinetic benefits, the CER process with two-electron transfers reaction. As of now, precious noble metal catalysts such as ruthenium and iridium-based oxides have been explored as a catalyst for seawater electrolysis. However, their high cost does not recommend the use of these catalysts for the large-scale production and limits its commercialization. Here, we are exploring the non-precious Mn based catalyst for OER vs. CER and make make seawater electrolysis as a commercial favourable process. We have explored various polymorphs of MnO2, such as α, β, γ, and δ-MnO2, considering the MnO2 as diffusion blocking layer for the selective OER process during the seawater electrolysis. The polymorphic engineering provide the window to tune the catalytic properties to make it selective towards the OER. Further, the results suggest that α- and β-MnO2 are OER selective however, the γ-, and δ- MnO2 are CER selective. We have identified the reaction mechanism using various electrochemical tools and shown the structure-activity-selectivity trends for the polymorphic structure of MnO2.

Optimized Doping of Diffusion Blocking Layers and Their Impact on the Performance of Perovskite Photovoltaics.

The roll-to-roll printing production process for hybrid organic-inorganic perovskite solar cells (PSCs) demands thick and high-performance solution-based diffusion blocking layers. Inverted (p-i-n) PSCs usually incorporate solution-processed PC70BM as the electron-transporting layer (ETL), which offers good electron charge extraction and passivation of the perovskite active layer grain boundaries. Thick fullerene diffusion blocking layers could benefit the long-term lifetime performance of inverted PSCs. However, the low conductivity of PC70BM significantly limits the thickness of the PC70BM buffer layer for optimized PSC performance. In this work, we show that by applying just enough N-DMBI doping principle, we can maintain the power conversion efficiency (PCE) of inverted PSCs with a thick (200 nm) PC70BM diffusion blocking layer. To better understand the origin of an optimal doping level, we combined the experimental results with simulations adapted to the PSCs reported here. Importantly, just enough 0.3% wt N-DMBI-doped 200 nm PC70BM diffusion blocking layer-based inverted PCSs retain a high thermal stability at 60 °C of up to 1000 h without sacrificing their PCE photovoltaic parameters.

Low-temperature processing technique of Ruddlesden-Popper cathode for high-performance solid oxide fuel cells

The Ruddlesden-Popper phase lanthanum nickelate, La2NiO4+δ (LNO), offers excellent material properties as a cathode for solid oxide fuel cells (SOFCs). However, taking full advantage of its intrinsic properties is difficult in realistic cells because of its high chemical reactivity with the electrolyte at elevated temperatures. Herein, we demonstrate high-performance SOFCs with an LNO-based cathode fabricated by a low-temperature processing route that suppresses harmful chemical reactions. The sintering capability of the composite cathode composed of LNO and gadolinia-doped ceria (GDC) was enhanced by mixing Fe-based sintering additive with GDC, which formed reliable interfacial bonding with the electrolyte at a temperature ~200 °C below the typical processing temperature. Because no interdiffusion between cathode and electrolyte occurs at such low temperatures, the cell is successfully fabricated without diffusion blocking layer, which simplifies the cell structure and manufacturing process. The cell with the LNO-based cathode outperformed state-of-the-art cells, particularly at lower operating temperatures. These results highlight that the processing parameters strongly affect the electrochemical performance of this LNO-based cathode and must be carefully engineered to fully exploit its superior intrinsic properties.

Al2O3 blocking layer inserted ZrO2 Metal-Insulator-Metal capacitor for the improved electrical and interfacial properties

Atomic layer deposition with O3 reactant is widely used to deposit thin and conformal films in a ZrO2 based metal-insulator-metal (MIM) capacitor. Post-deposition annealing (PDA) improves the MIM capacitor's performances by crystallizing tetragonal ZrO2 with high dielectric constant but it inevitably causes formation of excessive TiN/ZrO2 interface. Oxygen diffusion from ZrO2 to TiN bottom electrode oxidizes TiN to TiOx and TiOxNy during PDA, which increases the capacitance equivalent thickness of interlayer (CETint) and leakage current of the MIM capacitor. In this study, we inserted a Al2O3 thin film as the oxygen diffusion blocking layer (ODBL) between ZrO2 dielectric and bottom TiN electrode to improve the interfacial properties in TiN/ZrO2/TiN MIM capacitor. The angle-resolved X-ray photoelectron spectroscopy is employed to study the effects of Al2O3 OBDL on the chemical states of the interfacial layer in MIM capacitor, which confirmed that the Al2O3 ODBL inhibits the growth of TiN/ZrO2 interface. In addition, the electrical analysis of MIM capacitor showed that the CET of TiN/ZrO2 interface decreased from 0.493 to 0.209 nm and the leakage current highly decreased from 10−7 to 10−9 A/cm2 at 1 V although the dielectric constant slightly reduced from 35.1 to 30.7 with the insertion of Al2O3. This study offers a systematic investigation of interfacial layers in Al2O3 OBDL inserted ZrO2 MIM capacitor in the points of chemical and electrical characterization.

Block Iodide, Save Perovskite Modules

Stability of small area perovskite solar cells has been notably improved, but large area modules have not been proven stable. Recently in Joule, E. Bi and coworkers present a highly stable perovskite module that kept 90% of its initial efficiency after 1,000 h operation under illumination. The secret is an iodide diffusion blocking layer (DBL) added at the module interconnection. The DBL with 2D graphitic carbon nitride (g-C3N4) flakes can suppress iodide diffusion at the interconnection and prevent electrode corrosion.

Transparent and flexible electrode composed of a graphene multilayer interlayer-doped with MoO3

Abstract We demonstrate a flexible and transparent electrode consisting of a graphene multilayer that is interlayer-doped by layers of MoO3, a material that has attractive features as a graphene dopant but has not been used as such due to difficulties in fabrication. The fabrication of MoO3-interlayer-doped graphene multilayer (M-i-d GML) is enabled by successive applications of a modified wet-transfer of a graphene monolayer onto an elastomeric stamp precoated with a diffusion-blocking layer and its subsequent transfer onto a thermally evaporated MoO3 layer. By performing Raman spectroscopy and sheet resistance measurements, we show that charge-transfer doping of graphene occurs at both the top and bottom graphene–MoO3 interfaces of each graphene layer in a M-i-d GML. In comparison with a graphene multilayer doped only by a top MoO3 layer, M-i-d GMLs suffer less from the trade-off between optical transmittance and sheet resistance. Moreover, the characteristics of a green phosphorescent organic light-emitting device (OLED) employing a M-i-d GML bottom electrode are very similar to those of an OLED with an indium tin oxide anode, indicating that M-i-d GMLs are a promising candidate for transparent and flexible electrodes in optoelectronic and wearable applications.

Long Thermal Stability of Inverted Perovskite Photovoltaics Incorporating Fullerene‐Based Diffusion Blocking Layer

AbstractIn this article, the stability of inverted (p‐i‐n) perovskite solar cells is studied under accelerated heat lifetime conditions (60 °C, 85 °C, and N2 atmosphere). By using a combination of buffer layer engineering, impedance spectroscopy, and other characterization techniques, the interaction of the perovskite active layer with the top Al metal electrode through diffusion mechanisms is proposed as the major thermal degradation pathway for planar inverted perovskite photovoltaics (PVs) under 85 °C heat conditions. It is shown that by using thick solution processed fullerene buffer layer the perovskite active layer can be isolated from the top metal electrode and improve the lifetime performance of the inverted perovskite photovoltaics at 85 °C. Finally, an optimized reliable solution processed inverted perovskite PV device using thick fullerene diffusion blocking layer with over 1000 h accelerated heat lifetime performance at 60 °C is presented.

A numerical analysis and experimental demonstration of a low degradation conductive bridge resistive memory device

This study investigates a low degradation metal-ion conductive bridge RAM (CBRAM) structure. The structure is based on placing a diffusion blocking layer (DBL) between the device's top electrode (TE) and the resistive switching layer (RSL), unlike conventional CBRAMs, where the TE serves as a supply reservoir for metallic species diffusing into the RSL to form a conductive filament (CF) and is kept in direct contact with the RSL. The properties of a conventional CBRAM structure (Cu/HfO2/TiN), having a Cu TE, 10 nm HfO2 RSL, and a TiN bottom electrode, are compared with a 2 nm TaN DBL incorporating structure (Cu/TaN/HfO2/TiN) for 103 programming and erase simulation cycles. The low and high resistive state values for each cycle are calculated and the analysis reveals that adding the DBL yields lower degradation. In addition, the 2D distribution plots of oxygen vacancies, O ions, and Cu species within the RSL indicate that oxidation occurring in the DBL-RSL interface results in the formation of a sub-stoichiometric tantalum oxynitride with higher blocking capabilities that suppresses further Cu insertion beyond an initial CF formation phase, as well as CF lateral widening during cycling. The higher endurance of the structure with DBL may thus be attributed to the relatively low amount of Cu migrating into the RSL during the initial CF formation. Furthermore, this isomorphic CF displays similar cycling behavior to neural ionic channels. The results of numerical analysis show a good match to experimental measurements of similar device structures as well.

Enhancement of Endurance in HfO2-Based CBRAM Device by Introduction of a TaN Diffusion Blocking Layer

We propose a new method to improve resistive switching properties in HfO2 based CBRAM crossbar structure device by introducing a TaN thin diffusion blocking layer between the Cu top electrode and HfO2 switching layer. The Cu/TaN/HfO2/TiN device structure exhibits high resistance ratio of OFF/ON states without any degradation in switching during endurance test. The improvement in the endurance properties of the Cu/TaN/HfO2/TiN CBRAM device is thus attributed to the relatively low amount of Cu migration into HfO2 switching layer.

TiO2/ZnS/Ag/ZnS/TiO2다층막의 PDP 필터용 전극 특성

The <TEX>$TiO_2$</TEX>/ZnS/Ag/ZnS/<TEX>$TiO_2$</TEX> multilayered structure for the transparent electrodes in plasma display panel was designed by essential macleod program (EMP) and the multilayered film was deposited on a glass substrate by direct-current (DC)/radio-frequency (RF) magnetron sputtering system. During film deposition process, the Ag layer in <TEX>$TiO_2$</TEX>/Ag/<TEX>$TiO_2$</TEX> structure became oxidized and the filter characteristic was degraded easily. In this study, ZnS layer was adopted as a diffusion blocking layer between <TEX>$TiO_2$</TEX> and Ag to prevent the oxidation of Ag layer efficiently in <TEX>$TiO_2$</TEX>/ZnS/Ag/ZnS/<TEX>$TiO_2$</TEX> structure. Based on the AES depth profiling analysis, the Ag layer was effectively protected by the ZnS layer as compared with the <TEX>$TiO_2$</TEX>/Ag/<TEX>$TiO_2$</TEX> multilayered films without ZnS as an antioxidant layer. The 3 times stacked <TEX>$TiO_2$</TEX>/ZnS/Ag/ZnS/<TEX>$TiO_2$</TEX> films have low sheet resistance of <TEX>$1.22{\Omega}/{\square}$</TEX> and luminous transmittance was as high as 62% in the visible ranges.

The Pile-Ups Of Aluminum And Boron In The Sige(C)

ABSTRACTDopants diffusion, activation and pile-up due to rapid thermal annealing of implanted Al and B in a thin (∼200Å) Si cap layer on top of Si1-x-yGexCy layer were studied. Experimental results show that both the lattice strain and differential diffusion flux can cause atomic pile-up at the interface and the evidences of those effects were shown independently to each other in this paper. In addition, the pile-up can be extended from the interface to the surface by incorporating C in the underlying layer where B diffusion is much less than in the cap Si. Material analysis shows that both B atomic and activated concentrations in the Si cap layer are increased by 50 %, which suggests that the dopant activation can be increased and junction depth can be decreased at the same time using the inserted Si1-x-yGexCy diffusion blocking layer.

Annealing Effect on Interfaces of Atmospheric Pressure Chemical‐Vapor‐Deposited Multilayer Doped Silicon Oxides for Optical Waveguides

The postdeposition thermal effect on different silicon oxide‐based multilayers is investigated using x‐ray photoelectron spectroscopy (XPS) depth profiling. A multilayer consisting of borophosphosilicate glass (BPSG) and germophosposilicate glass (GPSG) used frequently as cladding and core layers in silica waveguides, is investigated. XPS depth profile results indicate that diffusion of Ge and B into both BPSG and GPSG, even with 30 mm of annealing at 800°C, makes two layers of germoborophosphosilicate glass (GBPSG) at the interfacial region, with considerable refractive index changes as compared with the initial GPSG material. During annealing, the dopants diffuse as neutral species rather than in oxide/suboxidized form. XPS depth profiling is also carried out using nondoped silicate glass or phosphosilicate glass as a diffusion blocking layer. The results show that both Ge and B diffuse less than in BPSG and GPSG Based on this investigation, waveguide structures are proposed which can compensate the dopant diffusion that is caused by post‐thermal treatment.